County law librarians work with a lot of family law attorneys and pro se litigants contending with family law issues (marriage, divorce, custody, support). Not a small percentage of them have questions about spousal support (and subsequent modification). If your practice (or your life) hasn’t been such that you keep up with the law on this subject on a regular basis, you’ll need to do some research in the primary sources (starting with your state’s “Digest,” usually), the secondary sources (e.g. treatises and periodicals), and in your state’s legal practice research resources.
(I highly recommend a West “Digest” Topic (e.g. Divorce or Husband and Wife) search for starters and make sure you read the Scope Notes.)
Lately, though, every time I hear a summary of the facts for these cases, I think of the book “The Feminine Mistake.”